The present invention is related in general to optocouplers, and in particular to a high speed optocoupler that exhibits improved performance in an analog signal mode.
In an optocoupler, a driver stage takes an input signal and converts it to an optical signal. The optical signal is then sensed by a detector stage, which converts it back to an electrical signal. Ideally, the two stages (driver and detector) introduce little or no delay or distortion into the signal being coupled.
Some common applications for optocouplers are isolated switching power supplies, medical sensor isolation, and isolation of process control transducers to name only a few. In particular, isolated switching power supplies typically use one or more optocouplers to provide isolation in a feedback loop. Optocouplers do an excellent job of isolation, minimizing circuit complexity and reducing cost. One of the disadvantages of using an optocoupler is its relatively low bandwidth. As switching frequencies and bandwidth for isolated power supplies continue to be increased to reduce size and accommodate high di/dt loads, the bandwidth of the optocoupler becomes a significant limitation on power supply performance.
For the reasons stated above and for additional reasons stated hereinafter, which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an improved optocoupler. The above-mentioned problems of optocouplers and other problems are addressed by the present invention, at least in part, and will be understood by reading and studying the following specification.